Turbulence and fire-spotting effects into wild-land fire simulators

摘要

This paper presents a mathematical approach to model the effects of phenomenawith random nature such as turbulence and fire-spotting into the existingwildfire simulators. The formulation proposes that the propagation of thefire-front is the sum of a drifting component (obtained from an existingwildfire simulator without turbulence and fire-spotting) and a randomfluctuating component. The modelling of the random effects is embodied in aprobability density function accounting for the fluctuations around the fireperimeter which is given by the drifting component. In past, this formulationhas been applied to include these random effects into a wildfire simulatorbased on an Eulerian moving interface method, namely the Level Set Method(LSM), but in this paper the same formulation is adapted for a wildfiresimulator based on a Lagrangian front tracking technique, namely the DiscreteEvent System Specification (DEVS). The main highlight of the present study isthe comparison of the performance of a Lagrangian and an Eulerian movinginterface method when applied to wild-land fire propagation. Simple idealisednumerical experiments are used to investigate the potential applicability ofthe proposed formulation to DEVS and to compare its behaviour with respect tothe LSM. The results show that DEVS based wildfire propagation modelqualitatively improves its performance (e.g., reproducing flank and back fire,increase in fire spread due to pre-heating of the fuel by hot air andfirebrands, fire propagation across no fuel zones, secondary fire generation,\dots). Though the results presented here are devoid of any validation exerciseand provide only a proof of concept, they show a strong inclination towards anintended operational use. The existing LSM or DEVS based operational simulatorslike WRF-SFIRE and ForeFire respectively can serve as an ideal basis for thesame.